Hi, I'm trying to use this dead simple enum in a shared library:

package x.y.z
enum ProjectTypes {
    python,
    node
    // workaround https://issues.jenkins.io/browse/JENKINS-33023
    ProjectTypes() {}
}

but I'm hitting a ridiculous bunch of errors. This time I'm really desperate and didn't find any workaround.
The enum is placed in the library's /src directory and called from a method in a /vars script, that does type coercion from a string such as this, let's call it tripMine.groovy:

import x.y.z.ProjectTypes
def call(String projectTypeStr) {
    return projectTypeStr as ProjectTypes
}

This is supposed to work thanks to enum's valueOf() static method, but if I call it from a basic scripted pipeline (where the library is included on the folder-level):

@Library('my-library@my-branch') _
node {
    stage('trip') {
        def trouble = tripMine('python')
    }
} 

I get this exception back:

org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: No such static method found: staticMethod x.y.z.ProjectTypes valueOf java.lang.Class java.lang.String 

This is the main trouble, but the fun continues.

The exception is from the script-security-plugin, I'm an admin, so I can easily whitelist that in the In-process script approval page, but yikes, it's not there. I found JENKINS-53700, but that's why I abandoned the usual declarative pipeline and used the scripted one. Still no dice.

Next I tried to add the method to the enum:

static ProjectTypes valueOf(Class clazz, String str) {
    return python
} 

This time the execution passed (why?), but reimplementing the whole method defies the very reason I used enum in the first place.

Is there something sensible I can do to make this work? I've also found this "improvement" suggestion JENKINS-56948, which looks quite like the same thing, but I don't believe that's an improvement material. Hope I'm right   Thanks a lot!